Observation Fusion: Earth Observation Coverages

OWS-8 Earth Observation Coverages

The Sensor Web Enablement (SWE) architecture was designed to enable web-accessible sensor assets through common interfaces and encodings. Sensor assets may include the sensors themselves, observation archives, simulations, and observation processing algorithms. The Observation Fusion thread continues the further refinement and extension of SWE with an emphasis on sensor fusion.

In 2010, OGC approved the OGC Web Coverage Service (WCS) Interface Standard, Version 2.0. The WCS 2.0 has several significant enhancements over previous versions. WCS 2.0 is harmonized with the Geography Markup Language (GML) coverage model, leading to increased interoperability across OGC standards. It supports the following encodings: GeoTIFF, HDF, NetCDF, and JPEG2000. WCS 2.0 brought together, for this testbed, the resources of both U.S. and European space agencies (NASA, ESA) to help develop a common profile for best interoperability.

Development had already begun for an Earth Observation Application Profile (WCS 2.0 EO-AP) before this testbed. Since the release of the WCS 2.0 suite of documents, a WCS 2.0 EO-AP has been drafted in ESA’s HMA project. The EO-AP builds on previous work with WCS 1.0. The EO-AP draft includes NetCDF , GeoTiff or JPEG2000 as possible return formats. The EO-AP draft was further developed in OWS-8 to include compliance testing with multiple datasets and will be coordinated with development of a Compliance Test Suite.

OWS-8 EO Coverages Engineering Reports

These Engineering Reports are publicly available, see the Deliverables Page of this website. Most component deliverables are prototypes, not available for commercial use. These will all be maintained for at least a few months after the testbed. Contact the relevant participant organization or OGC staff if questions.

EO Coverages Scenario: State of Emergency in Brazil due to Amazon basin droughts

On the heels of the once-in-a-century drought in 2005 comes an even more severe drought in 2010, which also was intense and coincided with the dry season. Direct evidence of the impact in terms of the spatial extent and severity of the 2010 drought on Amazonian vegetation is currently lacking. Hence, NASA is interested in developing methods to automate drought analysis using commonly available satellite datasets of precipitation and vegetation greenness. Furthermore, NASA’s interest in the OGC Web Coverage Service protocol reflects the desire to make data characteristics, such as granularity, projection, and formats, more transparent in order to accommodate diverse communities wishing to fully exploit NASA’s vast data archives for new applications that require data transformations.

NASA satellite sensors, such as MODIS, showed an average pattern of greenness of vegetation on South America: Amazon forests which have very high leaf area are shown in red and purple colors, the adjacent cerrado (savannas) which have lower leaf area are shown in shades of green, and the coastal deserts are shown in yellow colors.
(Credit: Boston University/NASA)

Coverages Demo 1 – Data Services, EO WCS

Coverages Demo 2 – EO WCS Server

Coverages Demo 3: Amazon basin drought analysis using WPS

Satellite data can go through two stages of analysis. First, pre-processing occurs to filter out cloud cover, correct for aerosol-corruption effects, and to remove residual atmosphere-corruption to produce the best possible signals from the vegetation. In OWS-8, participants took data from NASA and ESA and applied these pre-processing steps before serving the imagery via EO-WCS.

This allowed the imagery to be available in a very flexible manner, including the capability to mosaick, re-project and warp adjacent satellite images to match the coordinate reference systems of other datasets. Only then can any actual analysis occur. And in a moment you will see mathematical functions applied to the imagery to study drought, identifying the change in precipitation and greeness over time.

Analysis was performed in desktop software, a web processing service (WCS), and a web coverage processing service (WCPS).

Coverages Demo 5: Oil spill image analysis using WCPS

While the drought analysis used Earth Observation Web Coverage Services as data input, which is at it’s core a standard OGC Web Coverage Service, the data sets can be re-used in completely different domains as a standard WCS – there’s no need for others to know these data are also being exploited through Earth Observation systems.

We now move to a disaster and emergency response scenario, where these services join with a host of others to help emergency management teams respond to an earthquake.